Rutkauskas, Arūnas

Anthelmintic resistance is one of the major challenges in modern sheep parasitology, reducing the effectiveness of gastrointestinal nematode control and threatening sustainable sheep production. Despite its increasing importance across Europe, representative data on the prevalence of anthelmintic resistance and its associated risk factors in Lithuania have been limited. The aim of this dissertation was to investigate the prevalence of anthelmintic resistance in sheep gastrointestinal nematodes in Lithuanian sheep farms and to identify farm-related risk factors associated with its development. The study evaluated parasite control practices, determined the prevalence of gastrointestinal nematodes, assessed resistance to benzimidazoles, macrocyclic lactones, and levamisole using the micro-agar larval development test, identified resistant nematode genera, and analysed associations between resistance, farm management, and treatment strategies. Farms were selected using a systematic sampling approach from members of the Lithuanian Sheep Breeders Association, providing the first nationally representative data on anthelmintic resistance in Lithuanian sheep farms. The findings provide a scientific basis for more rational anthelmintic use, implementation of risk-based parasite control strategies, and the development of practical recommendations aimed at preserving anthelmintic efficacy and supporting sustainable sheep production.

Gamma-glutamyl transferase (GGT) is routinely used as a biomarker of hepatobiliary function in dairy cows, but its association with sensor-derived production traits and metabolic adaptation during early lactation remains poorly understood. This study investigated relationships between serum GGT activity, automated monitoring data, and blood biochemical parameters in 164 clinically healthy Holstein cows between 10 and 30 days in milk (DIM). Cows were classified into three groups according to serum GGT activity: low (≤20 U/L; n = 52), moderate (>20–≤40 U/L; n = 90), and high (>40 U/L; n = 22). Milk yield differed significantly among the three GGT groups, with median values of 28.90, 35.30, and 37.45 kg/day in the low, moderate, and high GGT groups, respectively (p = 0.047). Median milk protein concentration decreased from 3.87% in the low GGT group to 3.64% and 3.39% in the moderate and high GGT groups, respectively (p < 0.001). Among the blood biochemical parameters, median CRP concentrations increased from 6.82 to 10.28 and 13.00 mg/L, TP concentrations from 67.15 to 69.45 and 76.60 g/L, and LDH activity from 1098.50 to 1164.00 and 1581.00 U/L, whereas median glucose concentrations decreased from 3.61 to 3.19 and 3.17 mmol/L across the low, moderate, and high GGT groups, respectively (all p < 0.05). These findings suggest that increased GGT activity is associated with differences in milk production and selected blood biochemical parameters during early lactation. Together, these associations contribute to a better understanding of the relationships between GGT activity, routinely monitored production traits, and biochemical characteristics in fresh dairy cows.

This study evaluated the impact of essential oil supplementation, primarily containing seed oil from coriander, along with eugenol, geranyl acetate and geraniol, on the blood metabolic profile and overall health of dairy cattle during the transition period. Milking was done using a milking robot, all cows were given total mixed ration (TMR) twice a day, at 07:00 a.m. and 07:00 p.m. A total of 140 multiparous Holstein cows were divided into two groups: a test group (n=70) receiving essential oil supplementation (1 g/cow/day) and a control group (n=70). The cows were monitored from 30 days before calving to 90 days post-calving. Results showed that cows in the test group produced 4.5% to 7% more milk compared to the control group across different lactation periods (5-90 days in milk). Milk composition was also improved with higher milk fat and protein percentages. Essential oil supplementation positively influenced feed efficiency and metabolic indicators such as albumin. These results suggest that essential oil supplementation enhances milk yield, composition, and efficiency during the critical transition period.

This study aimed to investigate the relationship between enteric methane (CH4) emissions and metabolic, physiological, and behavioural factors in early lactation Holstein cows. Forty-two cows were observed over a span of five consecutive weeks (0–100 days in lactation). CH4 concentration (ppm) was quantified with a portable laser detector, whereas rumination duration, temperature, and water consumption were documented using intraruminal boluses. Weekly blood samples were examined for beta-hydroxybutyrate (BHB), C-reactive protein (CRP), urea (UREA), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT) levels. The evaluation of milk yield and composition was conducted utilising in-line infrared sensors. Cows were classified against clinical reference intervals, and associations were tested via group comparisons, correlations, multiple linear regression, linear mixed models (cow ID random effect), ROC analysis, and by relating CH4 to dry matter intake (DMI). Cows with elevated BHB (≥1.2 mmol/L) emitted 87.8% more CH4 than cows within range and showed higher CH4 yield per kg DMI; elevated GGT was likewise associated with higher CH4 (+25.2%). CH4 correlated positively with BHB (r = 0.54, p < 0.01), and negatively with rumination (r = −0.38, p < 0.05). Regression explained 30.2% of CH4 variance (adjusted R2 = 0.302): BHB was a positive predictor (β = 0.55, p = 0.047), whereas LDH was negative (β = −0.21, p = 0.033). A three-way interaction (BHB group × AST × GGT) was significant in the mixed model (F = 6.91, p = 0.002). For discrimination of high emitters, BHB achieved AUC = 0.889; among on-farm traits, milk yield (AUC = 0.823) and lactose (AUC = 0.701) performed best. DMI related inversely to CH4 yield (r = −0.69, p = 0.058). The findings indicate that enteric methane production during early lactation is not exclusively influenced by diet but is significantly associated with systemic metabolic health. Integrating physiological and production characteristics may improve precision-driven methane monitoring and mitigation strategies in dairy systems.

Objectives: The transition period is defined by significant physiological and behavioural changes in dairy cows, which can affect enteric methane emissions. While rumination duration is often used as an indicator of health and welfare, its association with methane emissions is inconsistent across various studies. This study was aimed at exploring if categorising cows based on average daily rumination time could uncover significant variations in methane emissions and to determine particular ingestive and activity behaviours linked to methane output. Furthermore, we applied Principal Component Analysis (PCA) to condense complex behavioural data into comprehensible patterns associated with methane production. This study aims to elucidate behavioural predictors of methane through the integration of classification and multivariate analytics, thereby facilitating the formulation of precision-based emission mitigation strategies. Materials and Methods: Thirteen clinically healthy Holstein cows were observed from 40 days before parturition to 21 days after parturition. Feeding behaviours and rumination were continuously monitored using RumiWatch noseband sensors [Itin+Hoch GmbH, Switzerland]. Methane emissions were quantified twice daily utilising a laser methane detector [HESAI HS4000]. Cows were classified retrospectively into three categories based on average rumination time: low (<404 min/day), medium (404–500 min/day), and high (>500 min/day). Principal Component Analysis was conducted on behavioural data to identify components linked to methane emissions. Results: Methane emissions were highest in medium-rumination cows, followed by high and low groups; however, the differences were not statistically significant (p > 0.05). In cows with low rumination, methane exhibited a negative correlation with rumination chews (r = -0.52, p < 0.05). In cows showing high rumination, methane levels were inversely correlated with drinking gulps (r = -0.42, p < 0.05) and bolus count (r = -0.37, p < 0.05). The findings indicate that methane production is more closely associated with particular ingestive behaviours than with the duration of rumination itself. PCA identified six components that account for 79.97% of the overall behavioural variance. Component 5 exhibited a significant negative loading for methane (−0.62) and positive loadings for "Other Chews" and "Activity," suggesting that heightened non-rumination jaw movements and locomotor behaviour may forecast reduced methane emissions. Conclusions: Although average rumination time alone did not significantly account for methane variability, multivariate behavioural traits identified through PCA indicated crucial predictors of methane emissions. The integration of behavioural classification with sensor-based analytics may enhance targeted enteric methane mitigation strategies in dairy herds.

Milk lactose concentration has been proposed as a noninvasive indicator of metabolic health in dairy cows, particularly during early lactation when metabolic demands are elevated. This study aimed to investigate the relationship between milk lactose levels and physiological, biochemical, and behavioral parameters in early-lactation Holstein cows. Twenty-eight clinically healthy cows were divided into two groups: Group 1 (milk lactose < 4.70%, n = 14) and Group 2 (milk lactose ≥ 4.70%, n = 14). Both groups were monitored over a 21-day period using the Brolis HerdLine in-line milk analyzer (Brolis Sensor Technology, Vilnius, Lithuania) and SmaXtec intraruminal boluses (SmaXtec Animal Care Technology®, Graz, Austria). Parameters including milk yield, milk composition (lactose, fat, protein, and fat-to-protein ratio), blood biomarkers, and behavior were recorded. Cows with higher milk lactose concentrations (≥4.70%) produced significantly more milk (+12.76%) and showed increased water intake (+15.44%), as well as elevated levels of urea (+21.63%), alanine aminotransferase (ALT) (+22.96%), glucose (+4.75%), magnesium (+8.25%), and iron (+13.41%) compared to cows with lower lactose concentrations (<4.70%). A moderate positive correlation was found between milk lactose and urea levels (r = 0.429, p < 0.01), and low but significant correlations were observed with other indicators. These findings support the use of milk lactose concentration as a practical biomarker for assessing metabolic and physiological status in dairy cows, and highlight the value of integrating real-time monitoring technologies in precision livestock management.

Inflammatory processes within the body have been hypothesised to be causative agents of various health complications, including reproductive issues. This study investigates the effects of mastitis on ovarian morphometry and fertility outcomes while also comparing the effectiveness of different synchronisation protocols in affected cows. Healthy multiparous Holstein dairy cows, in their second to fifth lactations and with an average milk yield of approximately 12,000 kg in the preceding lactation, were selected for this study. The average milk yield per lactation was approximately 12,000 kg, with an average daily milk yield of 30 kg. The aim of this study was to determine the impact of mastitis on the reproductive cycle, ovarian morphometry, and function in dairy cows, as well as its effect on synchronisation efficiency. This study focused on both clinically healthy cows and those diagnosed with clinical mastitis postpartum. Three different synchronisation protocols—OvSynch, G7G, and Presynch—were evaluated at 60 days in milk (DIM). A total of 110 cows were included in this study, with 53 being clinically healthy and 57 affected by mastitis. The results indicated that inflammation affects ovarian morphometric parameters such as the area and the number of functional structures. In addition, the G7G protocol was observed to result in higher conception rates in cows suffering from mastitis following the second insemination. This study demonstrated that cows that developed mastitis within the first 30 DIM exhibited higher conception rates after the first insemination compared to those in cows that developed mastitis later in lactation.

The milk fat-to-protein ratio (FPR) is a valuable indicator of metabolic health in dairy cows, especially during early lactation when cows are most susceptible to negative energy balance. This study aimed to evaluate the relationship between FPR, milk composition, blood biochemical parameters, and behavioral indicators in early-lactation Holstein cows. Twenty-seven cows between 9 and 59 days in milk were monitored and categorized into three groups: low-grade ruminal acidosis (LGRA; FPR < 1.2), healthy (H; FPR 1.2-1.5), and subclinical ketosis (SCK; FPR > 1.5). Milk composition was assessed in real time using the Brolis HerdLine in-line analyzer, while rumination time, reticulorumen temperature, water intake, and activity were recorded using SmaXtec boluses. Blood samples were collected weekly to analyze metabolic and biochemical parameters. Cows in the SCK group exhibited significantly lower milk lactose and protein concentrations, shorter rumination time, lower iron levels, and higher milk fat content, NEFA concentrations, and activity levels compared to the LGRA and healthy groups. The study demonstrated that elevated FPR is associated with metabolic and behavioral changes indicative of subclinical metabolic disorders, particularly subclinical ketosis. The integration of real-time milk composition data, behavioral monitoring, and blood biochemical analysis enables a comprehensive and non-invasive approach for early detection and management of metabolic imbalances in dairy herds. This study highlights the potential of precision monitoring technologies to improve animal welfare and productivity by supporting proactive herd health management.

In dairy cattle, abomasal ulcers are a serious but sometimes disregarded ailment that can have detrimental effects on health and cause financial losses. Due to inconclusive clinical symptoms, abomasal ulcers are typically misdiagnosed and treated improperly. Specialized diagnostic methods should be considered to ensure a correct diagnosis and the well-being of cattle. This report focuses on a 4-year-old Holstein-Friesian cow which began her third lactation two weeks before she started showing general clinical signs of an elevated fat–protein ratio in the milk and was diagnosed with an abomasum displacement. The clinical signs can also be mistaken for other conditions such as traumatic reticuloperitonitis and left dislocated abomasum. The patient was brought to the LUHS Large Animal Clinic, and after a short while, sudden death occurred. The autopsy concluded that death had occurred due to hypovolemic shock caused by abomasal ulcer perforation, which caused bleeding into the abomasum and intestines. Also, the type 3 ulcer caused severe peritonitis and anemia, and feed and fibrin could be seen on the outside of organs in the abdomen. Blood clots mixed with feed had formed in the inside of the abomasum and intestinal tract. Based on the work of previous scientific studies, it has been established that the occurrence of ulcers is more frequent in dairy cows during the first four to six weeks of lactation. And the most probable cause could be intensive feeding and dietary changes. Ulcers in the abomasum are very difficult to diagnose, because they require special diagnostic equipment such as an ultrasound or surgical interventions. Due to the similarity with other diseases, this pathological condition of the abomasum is most frequently only identified in post-mortem examinations.

Rising concerns about greenhouse gas emissions from dairy farming emphasize the need for strategies to reduce methane (CH₄) emissions from cattle. Enteric CH₄, generated by rumen microbial fermentation, accounts for 35–55% of on-farm greenhouse gas emissions, with dairy production responsible for over 70% of agricultural outputs [1]. This study evaluates nutritional strategies to mitigate enteric CH₄, focusing on natural feed additives to improve nutrient utilization and lower emissions. Certain studies propose that substituting grass silage with maize silage enhances rumen fermentation of propionate over acetate, thereby diminishing CH₄ emissions in dairy cows. When maize silage entirely supplanted grass silage in the diet of dairy cows, CH₄ emissions diminished by 8–11% [2]. Feeding cows the red seaweed Chondrus crispus, comprising 6% of the dry matter, resulted in a 13.9% reduction in CH₄ [3] large-scale adoption depends on technical and financial factors, as well as validation from pilot studies.Methods

A survey was developed to identify barriers and drivers towards the adoption of CH₄-reducing algal-based feeds. Concurrently, a randomized complete block design study was conducted to investigate the effect of C. crispus on enteric CH_{4 emissions and milk production in a typical Maine organic dairy farm. Twenty-two organically certified Holstein and Jersey cows averaging 29 ± 6.8 kg of milk/d and 150 ± 69 days in milk, were blocked and randomly assigned to a control diet without C. crispus (0CC. Cows fed daily with a 1 g blend of essential oils exhaled less CH₄ (444 ± 12.5 L/d) than cows fed a feed without the mixture (479 ± 12.5 L/d) [4]mainly in the form of methane. Essential oils are a group of plant secondary metabolites obtained from volatile fractions of plants that have been shown to exert changes in the rumen fermentation and may alter feed efficiency and to reduce methane production. The objective of this study was to investigate the effect on rumen microbial population, CH4 emissions and milking performance of a mixture of essential oils (Agolin Ruminant, Switzerland. The utilization of tannin or saponin-rich flora has become increasingly favoured for mitigating or eradicating protozoa in the rumen. Another study has shown that a commercial citrus extract diminished methane production while enhancing propionate concentration and the concentration of propionate-producing bacteria Megasphaera elsdenii [5]. The incorporation of 41 g of oilseed rape oil per kg of dry matter in the diet resulted in a 22.5% reduction in daily CH4 emissions from dairy cows [6]. Incorporating specific compounds into cattle diets can reduce methane emissions, improve feed efficiency, and support animal health, offering a sustainable approach to mitigating agriculture’s climate impact while maintaining farm profitability.}